Updated

A senior officer at the military command in charge of all U.S. nuclear war-fighting forces is a suspect in a gambling investigation and has been suspended from his duties, two senior U.S. officials confirmed to Fox News.

Navy Vice Adm. Tim Giardina has not been arrested or charged, Iowa Division of Criminal Investigation special agent David Dales said Saturday. The state investigation is ongoing.

A well placed source told Fox News Saturday morning that the suspension was related to gambling, while the Associated Press reports that the case involves counterfeit chips at an Iowa Casino.

Giardina, deputy commander at U.S. Strategic Command, was suspended on Sept. 3 and is under investigation by the Naval Criminal Investigative Service, a Strategic Command spokeswoman said.

The highly unusual action against a high-ranking officer at Strategic Command was made more than three weeks ago but not publicly announced at that time. The command is located at Offutt Air Force Base near Omaha, Neb.

Air Force Gen. Robert Kehler, who heads Strategic Command, suspended Giardina, according to the command's top spokeswoman, Navy Capt. Pamela Kunze. Giardina is still assigned to the command but is prohibited from performing duties related to nuclear weapons and other issues requiring a security clearance, she said.

Kehler has recommended to Defense Secretary Chuck Hagel that Giardina be reassigned, Kunze said. Giardina has been the deputy commander of Strategic Command since December 2011. He is a career submarine officer and prior to starting his assignment there was the deputy commander and chief of staff at U.S. Pacific Fleet.

DCI agents stationed at the Horseshoe Casino in Council Bluffs, Iowa, discovered the counterfeit chips, Dales said. He would not say when the discovery was made or how much in counterfeit chips was found, only that "it was a significant monetary amount."

Council Bluffs is located across the Missouri River from Omaha.

"We were able to detect this one pretty quickly and jump on it," Dales said. He declined to give specifics on how authorities determined that casino chips had been counterfeited or how Giardina might have been involved.

Strategic Command oversees the military's nuclear fighter units, including the Navy's nuclear-armed submarines and the Air Force's nuclear bombers and nuclear land-based missiles.

Kunze said Strategic Command did not announce the suspension because Giardina remains under investigation and action on Kehler's recommendation that Giardina be reassigned is pending. The suspension was first reported by the Omaha World-Herald.

Kunze said a law enforcement investigation of Giardina began June 16. Kehler became aware of this on July 16, and the following day he asked the Naval Criminal Investigative Service to begin a probe.

Fox News' Jennifer Griffin and The Associated Press contributed to this report.